check your content manager watch if all package are uptodate
then check to the marketplace, in free content sub category (scroll down, it s at the end of main market page) where all WU and city update are listed
I watched if I had all WU, and city update up to date and reinstalled the last WU,
hope this will help
if it s already installed, try going to content manager , uninstall it, relaunch the sim, then go to marketplace to reinstall it
in my case it was the WU 15 (nordics & greenland) causing the issue, since recently it s City Update 5: European Cities who received an update maybe on your end it s this one to check